This interagency agreement with the U.S. National Animal Disease Center in Ames, Iowa is part of NIAIDs Centers of Excellence for Influenza Research and Surveillance program. The goals of this project are to identify gene segments responsible for the success of the swine H3N2 virus and to determine the compatibilities between polymerase components of different influenza viruses. Swine viruses isolated during surveillance efforts will be characterized under this project as well.